Introduction: The relationship between brain activity and motion discrimination performance was examined to test the hypothesis that a particular human brain area, known as MT+, subserves visual motion perception. Methods: Speed discrimination thresholds (the speed increment that was just barely detectable) were measured in ten subjects. Functional magnetic resonance imaging (fMRI) was used to measure brain activity in in response to the same moving visual patterns. Results/Conclusions: Strong correlations were observed between individual differences in MT+ activity and motion discrimination performance, thus providing the strongest evidence to date that neuronal signals in this human brain area support visual motion perception.